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class="fa-fw fas fa-heart"></i><span> 关于</span></a></div></div><div id="toggle-menu"><a class="site-page"><i class="fas fa-bars fa-fw"></i></a></div></div></nav><div id="post-info"><h1 class="post-title">Chapter 12: Dynamic Memory</h1><div id="post-meta"><div class="meta-firstline"><span class="post-meta-date"><i class="far fa-calendar-alt fa-fw post-meta-icon"></i><span class="post-meta-label">发表于</span><time class="post-meta-date-created" datetime="2022-05-14T06:27:43.000Z" title="发表于 2022-05-14 14:27:43">2022-05-14</time><span class="post-meta-separator">|</span><i class="fas fa-history fa-fw post-meta-icon"></i><span class="post-meta-label">更新于</span><time class="post-meta-date-updated" datetime="2022-05-14T06:58:26.237Z" title="更新于 2022-05-14 14:58:26">2022-05-14</time></span><span class="post-meta-categories"><span class="post-meta-separator">|</span><i class="fas fa-inbox fa-fw post-meta-icon"></i><a class="post-meta-categories" href="/blog/categories/C/">C++</a></span></div><div class="meta-secondline"><span class="post-meta-separator">|</span><span class="post-meta-commentcount"><i class="far fa-comments fa-fw post-meta-icon"></i><span class="post-meta-label">评论数:</span><a href="/blog/2022/05/14/Chapter-12-Dynamic-Memory/#post-comment" itemprop="discussionUrl"><span class="valine-comment-count" data-xid="/blog/2022/05/14/Chapter-12-Dynamic-Memory/" itemprop="commentCount"></span></a></span></div></div></div></header><main class="layout" id="content-inner"><div id="post"><article class="post-content" id="article-container"><p>﻿# Exercises Section 12.1.1</p>
<h2 id="Ex12-1"><a href="#Ex12-1" class="headerlink" title="Ex12.1"></a>Ex12.1</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// b1 和 b2 共享数据，故而 b1 和 b2 都有 4 个元素</span></span><br><span class="line">StrBlob b1;</span><br><span class="line">&#123;</span><br><span class="line">	Strblob b2 = &#123;<span class="string">&quot;a&quot;</span>, <span class="string">&quot;an&quot;</span>, <span class="string">&quot;the&quot;</span>&#125;;</span><br><span class="line">	b1 = b2;</span><br><span class="line">	b2.<span class="built_in">push_back</span>(<span class="string">&quot;about&quot;</span>);</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="Ex12-2"><a href="#Ex12-2" class="headerlink" title="Ex12.2"></a>Ex12.2</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">class</span> <span class="title class_">StrBlob</span> </span><br><span class="line">&#123;</span><br><span class="line"><span class="keyword">public</span>:</span><br><span class="line">    <span class="keyword">typedef</span> std::vector&lt;std::string&gt;::size_type size_type;</span><br><span class="line">    <span class="built_in">StrBlob</span>();</span><br><span class="line">    <span class="built_in">StrBlob</span>(std::initializer_list&lt;std::string&gt; il);</span><br><span class="line">    <span class="function">size_type <span class="title">size</span><span class="params">()</span> <span class="type">const</span> </span>&#123; <span class="keyword">return</span> data-&gt;<span class="built_in">size</span>(); &#125;</span><br><span class="line">    <span class="function"><span class="type">bool</span> <span class="title">empty</span><span class="params">()</span> <span class="type">const</span> </span>&#123; <span class="keyword">return</span> data-&gt;<span class="built_in">empty</span>(); &#125;</span><br><span class="line">    <span class="comment">// add and remove elements</span></span><br><span class="line">    <span class="function"><span class="type">void</span> <span class="title">push_back</span><span class="params">(<span class="type">const</span> std::string &amp;t)</span> </span>&#123; data-&gt;<span class="built_in">push_back</span>(t); &#125;</span><br><span class="line">    <span class="function"><span class="type">void</span> <span class="title">pop_back</span><span class="params">()</span></span>;</span><br><span class="line">    <span class="comment">// element access</span></span><br><span class="line">    <span class="function">std::string &amp;<span class="title">front</span><span class="params">()</span></span>;</span><br><span class="line">    <span class="function">std::string &amp;<span class="title">back</span><span class="params">()</span></span>;</span><br><span class="line"><span class="keyword">private</span>:</span><br><span class="line">    std::shared_ptr&lt;std::vector&lt;std::string&gt;&gt; data;</span><br><span class="line">    <span class="comment">// throws msg if data[i] isn&#x27;t valid</span></span><br><span class="line">    <span class="function"><span class="type">void</span> <span class="title">check</span><span class="params">(size_type i, <span class="type">const</span> std::string &amp;msg)</span> <span class="type">const</span></span>;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line">StrBlob::<span class="built_in">StrBlob</span>(): <span class="built_in">data</span>(make_shared&lt;vector&lt;string&gt;&gt;()) &#123; &#125;</span><br><span class="line">StrBlob::<span class="built_in">StrBlob</span>(initializer_list&lt;string&gt; il): <span class="built_in">data</span>(make_shared&lt;vector&lt;string&gt;&gt;(il)) &#123; &#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">StrBlob::check</span><span class="params">(size_type i, <span class="type">const</span> string &amp;msg)</span> <span class="type">const</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="keyword">if</span> (i &gt;= data-&gt;<span class="built_in">size</span>())</span><br><span class="line">        <span class="keyword">throw</span> <span class="built_in">out_of_range</span>(msg);</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function">string &amp;<span class="title">StrBlob::front</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="built_in">check</span>(<span class="number">0</span>, <span class="string">&quot;front on empty StrBlob&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> data-&gt;<span class="built_in">front</span>();</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function">string &amp;<span class="title">StrBlob::back</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="built_in">check</span>(<span class="number">0</span>, <span class="string">&quot;back on empty StrBlob&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> data-&gt;<span class="built_in">back</span>();</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">StrBlob::pop_back</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="built_in">check</span>(<span class="number">0</span>, <span class="string">&quot;pop_back on empty StrBlob&quot;</span>);</span><br><span class="line">    data-&gt;<span class="built_in">pop_back</span>();</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="Ex12-3"><a href="#Ex12-3" class="headerlink" title="Ex12.3"></a>Ex12.3</h2><p>不需要；push_back 和 pop-back 会改变元素数量，故而不能定义 const 版本</p>
<h2 id="Ex12-4"><a href="#Ex12-4" class="headerlink" title="Ex12.4"></a>Ex12.4</h2><p>完全OK；size_type 类型为 unsigned 类型</p>
<h2 id="Ex12-5"><a href="#Ex12-5" class="headerlink" title="Ex12.5"></a>Ex12.5</h2><p>explicit 使构造函数显式化，优点是排除了隐式转换带来的一系列错误问题，缺点是降低了程序的灵活性。</p>
<h1 id="Exercises-Section-12-1-2"><a href="#Exercises-Section-12-1-2" class="headerlink" title="Exercises Section 12.1.2"></a>Exercises Section 12.1.2</h1><h2 id="Ex12-6"><a href="#Ex12-6" class="headerlink" title="Ex12.6"></a>Ex12.6</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;vector&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;memory&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="function">vector&lt;<span class="type">int</span>&gt; *<span class="title">fac</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="keyword">return</span> <span class="keyword">new</span> <span class="built_in">vector</span>&lt;<span class="type">int</span>&gt;();</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">add_element</span><span class="params">(vector&lt;<span class="type">int</span>&gt; *fac)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="type">int</span> i = <span class="number">0</span>;</span><br><span class="line">    <span class="keyword">while</span> (std::cin &gt;&gt; i)</span><br><span class="line">        fac-&gt;<span class="built_in">push_back</span>(i);</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">print_element</span><span class="params">(vector&lt;<span class="type">int</span>&gt; *fac)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="keyword">for</span> (<span class="type">const</span> <span class="keyword">auto</span> &amp;i: *fac)</span><br><span class="line">        std::cout &lt;&lt; i &lt;&lt; <span class="string">&quot; &quot;</span>;</span><br><span class="line">    std::cout &lt;&lt; endl;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="keyword">auto</span> pv = <span class="built_in">fac</span>();</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;input some numbers: &quot;</span>;</span><br><span class="line">    <span class="built_in">add_element</span>(pv);</span><br><span class="line">    <span class="built_in">print_element</span>(pv);</span><br><span class="line">    <span class="keyword">delete</span> pv;</span><br><span class="line">    <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="Ex12-7"><a href="#Ex12-7" class="headerlink" title="Ex12.7"></a>Ex12.7</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;vector&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;memory&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line">shared_ptr&lt;vector&lt;<span class="type">int</span>&gt;&gt; <span class="built_in">fac</span>()</span><br><span class="line">&#123;</span><br><span class="line">    <span class="keyword">return</span> make_shared&lt;vector&lt;<span class="type">int</span>&gt;&gt;();</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">add_element</span><span class="params">(shared_ptr&lt;vector&lt;<span class="type">int</span>&gt;&gt; fac)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="type">int</span> i = <span class="number">0</span>;</span><br><span class="line">    <span class="keyword">while</span> (std::cin &gt;&gt; i)</span><br><span class="line">        fac-&gt;<span class="built_in">push_back</span>(i);</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">print_element</span><span class="params">(shared_ptr&lt;vector&lt;<span class="type">int</span>&gt;&gt; fac)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="keyword">for</span> (<span class="type">const</span> <span class="keyword">auto</span> &amp;i: *fac)</span><br><span class="line">        std::cout &lt;&lt; i &lt;&lt; <span class="string">&quot; &quot;</span>;</span><br><span class="line">    std::cout &lt;&lt; endl;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="keyword">auto</span> pv = <span class="built_in">fac</span>();</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;input some numbers: &quot;</span>;</span><br><span class="line">    <span class="built_in">add_element</span>(pv);</span><br><span class="line">    <span class="built_in">print_element</span>(pv);</span><br><span class="line">    <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="Ex12-8"><a href="#Ex12-8" class="headerlink" title="Ex12.8"></a>Ex12.8</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="type">bool</span> <span class="title">b</span><span class="params">()</span> </span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="type">int</span> *p = <span class="keyword">new</span> <span class="type">int</span>;	<span class="comment">// 如果 new 失败，那么抛出 std::bad_alloc 异常</span></span><br><span class="line">	<span class="comment">// 修改代码：int *p = new (nothrow) int;</span></span><br><span class="line">	<span class="comment">// ...</span></span><br><span class="line">	<span class="keyword">return</span> p;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="Ex12-9"><a href="#Ex12-9" class="headerlink" title="Ex12.9"></a>Ex12.9</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// q 和 r 使用 new 方法，如果内存未及时释放，会造成内存泄漏</span></span><br><span class="line"><span class="type">int</span> *q = <span class="keyword">new</span> <span class="built_in">int</span>(<span class="number">42</span>), *r = <span class="keyword">new</span> <span class="built_in">int</span>(<span class="number">100</span>);</span><br><span class="line">r = q;</span><br><span class="line"><span class="comment">// q2 和 r2 使用智能指针，当把 q2 的值赋给 r2 时，q2 的引用计数增 1 而 r2 的引用计数减 1 变为 0，自动释放内存</span></span><br><span class="line"><span class="keyword">auto</span> q2 = <span class="built_in">make_shared</span>&lt;<span class="type">int</span>&gt;(<span class="number">42</span>), r2 = <span class="built_in">make_shared</span>&lt;<span class="type">int</span>&gt;(<span class="number">100</span>);</span><br><span class="line">r2 = q2;</span><br></pre></td></tr></table></figure>

<h1 id="Exercises-Section-12-1-3"><a href="#Exercises-Section-12-1-3" class="headerlink" title="Exercises Section 12.1.3"></a>Exercises Section 12.1.3</h1><h2 id="Ex12-10"><a href="#Ex12-10" class="headerlink" title="Ex12.10"></a>Ex12.10</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 正确</span></span><br><span class="line"><span class="function">shared_ptr&lt;<span class="type">int</span>&gt; <span class="title">p</span><span class="params">(<span class="keyword">new</span> <span class="type">int</span>(<span class="number">42</span>))</span></span>;</span><br><span class="line"><span class="built_in">proces</span>(<span class="built_in">shared_ptr</span>&lt;<span class="type">int</span>&gt;(p));</span><br></pre></td></tr></table></figure>

<h2 id="Ex12-11"><a href="#Ex12-11" class="headerlink" title="Ex12.11"></a>Ex12.11</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// get函数会得到一个内置指针，指向动态指针 p 管理的对象；将其作为参数传入 process 函数中则有两个独立的动态指针指向同一个对象；</span></span><br><span class="line"><span class="comment">// 当 process 结束后， p 指针的内存也释放了</span></span><br><span class="line"><span class="built_in">process</span>(<span class="built_in">shared_ptr</span>&lt;<span class="type">int</span>&gt;(p.<span class="built_in">get</span>()));</span><br></pre></td></tr></table></figure>

<h2 id="Ex12-12"><a href="#Ex12-12" class="headerlink" title="Ex12.12"></a>Ex12.12</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">auto</span> p = <span class="keyword">new</span> <span class="built_in">int</span>();</span><br><span class="line"><span class="keyword">auto</span> sp = <span class="built_in">make_shared</span>&lt;<span class="type">int</span>&gt;();</span><br><span class="line"></span><br><span class="line">a) <span class="built_in">process</span>(sp);		<span class="comment">// 合法；将智能指针 sp 副本传入 process 函数中</span></span><br><span class="line">b) <span class="built_in">process</span>(<span class="keyword">new</span> <span class="built_in">int</span>());	<span class="comment">// 不合法；普通指针不能隐式转换为智能指针</span></span><br><span class="line">c) <span class="built_in">process</span>(p);	<span class="comment">// 不合法；与 b 一样</span></span><br><span class="line">d) <span class="built_in">process</span>(<span class="built_in">shared_ptr</span>(<span class="type">int</span>)(p));		<span class="comment">// 合法；将普通指针显式转换为智能指针，然后将智能指针副本传入 process</span></span><br></pre></td></tr></table></figure>

<h2 id="Ex12-13"><a href="#Ex12-13" class="headerlink" title="Ex12.13"></a>Ex12.13</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// delete 只和 new 需要成对出现，不能用 delete 去释放 shared_ptr 内存，故而此代码会发生错误</span></span><br><span class="line"><span class="keyword">auto</span> sp = <span class="built_in">make_shared</span>&lt;<span class="type">int</span>&gt;();</span><br><span class="line"><span class="keyword">auto</span> p = sp.<span class="built_in">get</span>();</span><br><span class="line"><span class="keyword">delete</span> p;</span><br></pre></td></tr></table></figure>

<h1 id="Exercises-Section-12-1-4"><a href="#Exercises-Section-12-1-4" class="headerlink" title="Exercises Section 12.1.4"></a>Exercises Section 12.1.4</h1><h2 id="Ex12-14"><a href="#Ex12-14" class="headerlink" title="Ex12.14"></a>Ex12.14</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">struct</span> <span class="title class_">destination</span>;</span><br><span class="line"><span class="keyword">struct</span> <span class="title class_">connection</span>;</span><br><span class="line"></span><br><span class="line"><span class="function">connection <span class="title">connnect</span><span class="params">(destination*)</span></span>;</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">disconnect</span><span class="params">(connection)</span></span>;</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">end_connection</span><span class="params">(connection *p)</span> </span>&#123; <span class="built_in">disconnect</span>(*p); &#125;</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">f</span><span class="params">(destination &amp;d)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    connection c = <span class="built_in">connect</span>(&amp;d);</span><br><span class="line">    <span class="function">shared_ptr&lt;connection&gt; <span class="title">p</span><span class="params">(&amp;c, end_connection)</span></span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="Ex12-15"><a href="#Ex12-15" class="headerlink" title="Ex12.15"></a>Ex12.15</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">struct</span> <span class="title class_">destination</span>;</span><br><span class="line"><span class="keyword">struct</span> <span class="title class_">connection</span>;</span><br><span class="line"></span><br><span class="line"><span class="function">connection <span class="title">connnect</span><span class="params">(destination*)</span></span>;</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">disconnect</span><span class="params">(connection)</span></span>;</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">end_connection</span><span class="params">(connection *p)</span> </span>&#123; <span class="built_in">disconnect</span>(*p); &#125;</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">f</span><span class="params">(destination &amp;d)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    connection c = <span class="built_in">connect</span>(&amp;d);</span><br><span class="line">    <span class="function">shared_ptr&lt;connection&gt; <span class="title">p</span><span class="params">(&amp;c, [](connection *p) &#123; disconnect(*p); &#125;)</span></span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h1 id="Exercises-Section-12-1-5"><a href="#Exercises-Section-12-1-5" class="headerlink" title="Exercises Section 12.1.5"></a>Exercises Section 12.1.5</h1><h2 id="Ex12-16"><a href="#Ex12-16" class="headerlink" title="Ex12.16"></a>Ex12.16</h2><p><img src="https://img-blog.csdnimg.cn/20210531165353697.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl81MTcwMzE3NA==,size_16,color_FFFFFF,t_70#pic_center" alt="在这里插入图片描述"></p>
<h2 id="Ex12-17"><a href="#Ex12-17" class="headerlink" title="Ex12.17"></a>Ex12.17</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="type">int</span> ix = <span class="number">1024</span>, *pi = &amp;ix, *pi2 = <span class="keyword">new</span> <span class="built_in">int</span>(<span class="number">2048</span>);</span><br><span class="line"><span class="keyword">typedef</span> unique_ptr&lt;<span class="type">int</span>&gt; IntP;</span><br><span class="line"></span><br><span class="line">a) <span class="function">IntP <span class="title">p0</span><span class="params">(ix)</span></span>;		<span class="comment">// 非法；类型不匹配</span></span><br><span class="line">b) <span class="function">IntP <span class="title">p1</span><span class="params">(pi)</span></span>;		<span class="comment">// 合法</span></span><br><span class="line">c) <span class="function">IntP <span class="title">p2</span><span class="params">(pi2)</span></span>;	<span class="comment">// 合法</span></span><br><span class="line">d) <span class="function">IntP <span class="title">p3</span><span class="params">(&amp;ix)</span></span>;	<span class="comment">// 合法</span></span><br><span class="line">e) <span class="function">IntP <span class="title">p4</span><span class="params">(<span class="keyword">new</span> <span class="type">int</span>(<span class="number">2048</span>))</span></span>;	<span class="comment">// 合法</span></span><br><span class="line">f) <span class="function">IntP <span class="title">p5</span><span class="params">(p2.get())</span></span>;	<span class="comment">// 合法</span></span><br></pre></td></tr></table></figure>

<h2 id="Ex12-18"><a href="#Ex12-18" class="headerlink" title="Ex12.18"></a>Ex12.18</h2><p>因为可能同时有多个 shared_ptr 指向同一个对象，共享对象所有权故而不需要 release。</p>
<h1 id="Exercises-Section-12-3-1"><a href="#Exercises-Section-12-3-1" class="headerlink" title="Exercises Section 12.3.1"></a>Exercises Section 12.3.1</h1><h2 id="Ex12-27-28"><a href="#Ex12-27-28" class="headerlink" title="Ex12.27 28"></a>Ex12.27 28</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;fstream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;sstream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;string&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;vector&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;map&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;set&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;cstdlib&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> line_no = vector&lt;string&gt;::size_type;</span><br><span class="line">vector&lt;string&gt; file;    <span class="comment">// 文件以每行内容存储</span></span><br><span class="line">map&lt;string, set&lt;line_no&gt;&gt; wm;   <span class="comment">// 单词到行号 set 的映射</span></span><br><span class="line"></span><br><span class="line"><span class="function">string <span class="title">make_pluaral</span><span class="params">(<span class="type">size_t</span> ctr, <span class="type">const</span> string &amp;word, <span class="type">const</span> string &amp;ending)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="keyword">return</span> (ctr &gt; <span class="number">1</span>) ? word + ending : word;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function">string <span class="title">cleanup_str</span><span class="params">(<span class="type">const</span> string &amp;word)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    string ret;</span><br><span class="line">    <span class="keyword">for</span> (<span class="keyword">auto</span> it = word.<span class="built_in">begin</span>(); it != word.<span class="built_in">end</span>(); ++it)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">if</span> (!<span class="built_in">ispunct</span>(*it))</span><br><span class="line">            ret += <span class="built_in">tolower</span>(*it);</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">return</span> ret;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">input_text</span><span class="params">(ifstream &amp;is)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    string text;</span><br><span class="line">    <span class="keyword">while</span> (<span class="built_in">getline</span>(is, text))</span><br><span class="line">    &#123;</span><br><span class="line">        file.<span class="built_in">push_back</span>(text);       <span class="comment">// 保留此行文本</span></span><br><span class="line">        <span class="type">int</span> n = file.<span class="built_in">size</span>() - <span class="number">1</span>;    <span class="comment">// 当前行号</span></span><br><span class="line">        <span class="function">istringstream <span class="title">line</span><span class="params">(text)</span></span>;   <span class="comment">// 将每行分解为每个单词</span></span><br><span class="line">        string word;</span><br><span class="line">        <span class="keyword">while</span> (line &gt;&gt; word)</span><br><span class="line">        &#123;</span><br><span class="line">            <span class="comment">// 将当前行号插入到其行号 set 中</span></span><br><span class="line">            <span class="comment">// 如果单词不在 wm 中，则添加一项</span></span><br><span class="line">            wm[<span class="built_in">cleanup_str</span>(word)].<span class="built_in">insert</span>(n);</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function">ostream &amp;<span class="title">query_and_print</span><span class="params">(<span class="type">const</span> string &amp;sought, ostream &amp;os)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="comment">// 使用 find 而不是下标，避免将该单词添加到容器中</span></span><br><span class="line">    <span class="keyword">auto</span> loc = wm.<span class="built_in">find</span>(sought);</span><br><span class="line">    <span class="keyword">if</span> (loc == wm.<span class="built_in">end</span>())    <span class="comment">// 未找到</span></span><br><span class="line">    &#123;</span><br><span class="line">        os &lt;&lt; sought &lt;&lt; <span class="string">&quot;occurs 0 time&quot;</span> &lt;&lt; endl;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">else</span> </span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">auto</span> lines = loc-&gt;second;   <span class="comment">// 行号</span></span><br><span class="line">        os &lt;&lt; sought &lt;&lt; <span class="string">&quot;occurs &quot;</span> &lt;&lt; lines.<span class="built_in">size</span>() &lt;&lt; <span class="string">&quot; times&quot;</span> &lt;&lt; endl;</span><br><span class="line">        <span class="keyword">for</span> (<span class="type">const</span> <span class="keyword">auto</span> &amp;num : lines)</span><br><span class="line">            os &lt;&lt; <span class="string">&quot;\t(No &quot;</span> &lt;&lt; num + <span class="number">1</span> &lt;&lt; <span class="string">&quot;lines&quot;</span> &lt;&lt; *(file.<span class="built_in">begin</span>() + num) &lt;&lt; endl;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">return</span> os;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">runQueries</span><span class="params">(ifstream &amp;infile)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="comment">// infile指向我们要查询的文件</span></span><br><span class="line">    <span class="built_in">input_text</span>(infile);         <span class="comment">// 读入文本并建立查询 map</span></span><br><span class="line">    <span class="keyword">while</span> (<span class="literal">true</span>)</span><br><span class="line">    &#123;</span><br><span class="line">        cout &lt;&lt; <span class="string">&quot;enter word to look for or enter \&quot;q\&quot; to quit: &quot;</span>;</span><br><span class="line">        string s;</span><br><span class="line">        <span class="keyword">if</span> (!(cin &gt;&gt; s) || s == <span class="string">&quot;q&quot;</span>)</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="built_in">query_and_print</span>(s, cout) &lt;&lt; endl;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">(<span class="type">int</span> argc, <span class="type">char</span> *argv[])</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    ifstream infile;</span><br><span class="line">    <span class="keyword">if</span> (argc &lt; <span class="number">2</span> || !(infile.<span class="built_in">open</span>(argv[<span class="number">1</span>], infile)))</span><br><span class="line">    &#123;</span><br><span class="line">        cerr &lt;&lt; <span class="string">&quot;No input file !&quot;</span> &lt;&lt; endl;</span><br><span class="line">        <span class="keyword">return</span> EXIT_FAILURE;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="built_in">runQueries</span>(infile);</span><br><span class="line">    <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>


<h2 id="Ex12-29"><a href="#Ex12-29" class="headerlink" title="Ex12.29"></a>Ex12.29</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">do</span></span><br><span class="line">&#123;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;enter word to look for or enter \&quot;q\&quot; to quit: &quot;</span>;</span><br><span class="line">    string s;</span><br><span class="line">    <span class="keyword">if</span> (!(cin &gt;&gt; s) || s == <span class="string">&quot;q&quot;</span>)</span><br><span class="line">        <span class="keyword">break</span>;</span><br><span class="line">    <span class="built_in">query_and_print</span>(s, cout) &lt;&lt; endl;</span><br><span class="line">&#125; <span class="keyword">while</span> (<span class="literal">true</span>);</span><br></pre></td></tr></table></figure>

<p>使用 while 比使用 do_while 好</p>
<h1 id="Exercises-Section-12-3-2"><a href="#Exercises-Section-12-3-2" class="headerlink" title="Exercises Section 12.3.2"></a>Exercises Section 12.3.2</h1><h2 id="Ex12-30"><a href="#Ex12-30" class="headerlink" title="Ex12.30"></a>Ex12.30</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">class</span> <span class="title class_">QuertResult</span>;</span><br><span class="line"><span class="keyword">class</span> <span class="title class_">TextQuery</span></span><br><span class="line">&#123;</span><br><span class="line"><span class="keyword">public</span>:</span><br><span class="line">    <span class="keyword">using</span> line_no = std::vector&lt;std::string&gt;::size_type;</span><br><span class="line">    <span class="built_in">TextQuery</span>(std::ifstream &amp;);</span><br><span class="line">    <span class="function">QuertResult <span class="title">query</span><span class="params">(<span class="type">const</span> std::string &amp;)</span> <span class="type">const</span></span>;</span><br><span class="line"><span class="keyword">private</span>:</span><br><span class="line">    std::shared_ptr&lt;std::vector&lt;std::string&gt;&gt; file;</span><br><span class="line">    std::map&lt;std::string, std::shared_ptr&lt;std::set&lt;line_no&gt;&gt;&gt; wm;</span><br><span class="line">&#125;;</span><br><span class="line"></span><br><span class="line">TextQuery::<span class="built_in">TextQuery</span>(ifstream &amp;is): <span class="built_in">file</span>(<span class="keyword">new</span> vector&lt;string&gt;)</span><br><span class="line">&#123;</span><br><span class="line">    string text;</span><br><span class="line">    <span class="keyword">while</span> (<span class="built_in">getline</span>(is, text))</span><br><span class="line">    &#123;</span><br><span class="line">        file-&gt;<span class="built_in">push_back</span>(text);</span><br><span class="line">        <span class="type">int</span> n = file-&gt;<span class="built_in">size</span>() - <span class="number">1</span>;</span><br><span class="line">        <span class="function">istringstream <span class="title">line</span><span class="params">(text)</span></span>;</span><br><span class="line">        string word;</span><br><span class="line">        <span class="keyword">while</span> (line &gt;&gt; word)</span><br><span class="line">        &#123;</span><br><span class="line">            <span class="keyword">auto</span> &amp;lines = wm[word];</span><br><span class="line">            <span class="keyword">if</span> (!lines)</span><br><span class="line">                lines.<span class="built_in">reset</span>(<span class="keyword">new</span> set&lt;line_no&gt;);</span><br><span class="line">            lines-&gt;<span class="built_in">insert</span>(n);</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">class</span> <span class="title class_">QuertResult</span></span><br><span class="line">&#123;</span><br><span class="line"><span class="function"><span class="keyword">friend</span> std::ostream &amp;<span class="title">print</span><span class="params">(std::ostream &amp;, <span class="type">const</span> QueryResult &amp;)</span></span>;</span><br><span class="line"><span class="keyword">public</span>:</span><br><span class="line">    <span class="built_in">QuertResult</span>(std::string s, std::share_ptr&lt;std::set&lt;line_no&gt;&gt; p, std::shared_ptr&lt;std::vector&lt;std::string&gt;&gt; f) :</span><br><span class="line">        <span class="built_in">sought</span>(s), <span class="built_in">lines</span>(p), <span class="built_in">file</span>(f) &#123; &#125;</span><br><span class="line"><span class="keyword">private</span>:</span><br><span class="line">    std::string sought;</span><br><span class="line">    std::shared_ptr&lt;std::set&lt;line_no&gt;&gt; lines;</span><br><span class="line">    std::shared_ptr&lt;std::vector&lt;std::string&gt;&gt; file;</span><br><span class="line">&#125;;</span><br><span class="line"></span><br><span class="line"><span class="function">QueryResult <span class="title">TextQuery::query</span><span class="params">(<span class="type">const</span> string &amp;sought)</span> <span class="type">const</span> </span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="type">static</span> shared_ptr&lt;set&lt;line_no&gt;&gt; <span class="built_in">nodata</span>(<span class="keyword">new</span> set&lt;line_no&gt;);</span><br><span class="line">    <span class="keyword">auto</span> loc = wm.<span class="built_in">find</span>(sought);</span><br><span class="line">    <span class="keyword">if</span> (loc == wm.<span class="built_in">end</span>())</span><br><span class="line">        <span class="keyword">return</span> <span class="built_in">QuertResult</span>(sought, nodata, file);</span><br><span class="line">    <span class="keyword">else</span></span><br><span class="line">        <span class="keyword">return</span> <span class="built_in">QuertResult</span>(sought, loc-&gt;second, file);</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function">ostream &amp;<span class="title">print</span><span class="params">(ostream &amp;os, <span class="type">const</span> QuertResult &amp;qr)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    os &lt;&lt; qr.sought &lt;&lt; <span class="string">&quot; occurs &quot;</span> &lt;&lt; qr.lines-&gt;<span class="built_in">size</span>() &lt;&lt; <span class="string">&quot; &quot;</span></span><br><span class="line">       &lt;&lt; <span class="built_in">make_pluar</span>(qr.lines-&gt;<span class="built_in">size</span>(), <span class="string">&quot;time&quot;</span>, <span class="string">&quot;s&quot;</span>) &lt;&lt; endl;</span><br><span class="line">    <span class="keyword">for</span> (<span class="keyword">auto</span> num : *qr.lines)</span><br><span class="line">        os &lt;&lt; <span class="string">&quot;\t(line &quot;</span> &lt;&lt; num + <span class="number">1</span> &lt;&lt; <span class="string">&quot;) &quot;</span> &lt;&lt; *(qr.file-&gt;<span class="built_in">begin</span>() + num) &lt;&lt; endl;</span><br><span class="line">    <span class="keyword">return</span> os;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="Ex12-31"><a href="#Ex12-31" class="headerlink" title="Ex12.31"></a>Ex12.31</h2><p>set 会维护关键字的顺序，vector不会；vector 插入元素的效率更高；由于不需要维护关键字的顺序，故而使用 vector 效率更高。</p>
<h2 id="Ex12-32"><a href="#Ex12-32" class="headerlink" title="Ex12.32"></a>Ex12.32</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br><span class="line">105</span><br><span class="line">106</span><br><span class="line">107</span><br><span class="line">108</span><br><span class="line">109</span><br><span class="line">110</span><br><span class="line">111</span><br><span class="line">112</span><br><span class="line">113</span><br><span class="line">114</span><br><span class="line">115</span><br><span class="line">116</span><br><span class="line">117</span><br><span class="line">118</span><br><span class="line">119</span><br><span class="line">120</span><br><span class="line">121</span><br><span class="line">122</span><br><span class="line">123</span><br><span class="line">124</span><br><span class="line">125</span><br><span class="line">126</span><br><span class="line">127</span><br><span class="line">128</span><br><span class="line">129</span><br><span class="line">130</span><br><span class="line">131</span><br><span class="line">132</span><br><span class="line">133</span><br><span class="line">134</span><br><span class="line">135</span><br><span class="line">136</span><br><span class="line">137</span><br><span class="line">138</span><br><span class="line">139</span><br><span class="line">140</span><br><span class="line">141</span><br><span class="line">142</span><br><span class="line">143</span><br><span class="line">144</span><br><span class="line">145</span><br><span class="line">146</span><br><span class="line">147</span><br><span class="line">148</span><br><span class="line">149</span><br><span class="line">150</span><br><span class="line">151</span><br><span class="line">152</span><br><span class="line">153</span><br><span class="line">154</span><br><span class="line">155</span><br><span class="line">156</span><br><span class="line">157</span><br><span class="line">158</span><br><span class="line">159</span><br><span class="line">160</span><br><span class="line">161</span><br><span class="line">162</span><br><span class="line">163</span><br><span class="line">164</span><br><span class="line">165</span><br><span class="line">166</span><br><span class="line">167</span><br><span class="line">168</span><br><span class="line">169</span><br><span class="line">170</span><br><span class="line">171</span><br><span class="line">172</span><br><span class="line">173</span><br><span class="line">174</span><br><span class="line">175</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">class</span> <span class="title class_">StrBlobPtr</span>;</span><br><span class="line"><span class="keyword">class</span> <span class="title class_">QueryResult</span>;</span><br><span class="line"><span class="keyword">class</span> <span class="title class_">StrBlob</span> </span><br><span class="line">&#123;</span><br><span class="line">	<span class="keyword">friend</span> <span class="keyword">class</span> <span class="title class_">StrBlobPtr</span>;</span><br><span class="line"><span class="keyword">public</span>:</span><br><span class="line">	<span class="keyword">typedef</span> vector&lt;string&gt;::size_type size_type;</span><br><span class="line">	<span class="built_in">StrBlob</span>();</span><br><span class="line">	<span class="built_in">StrBlob</span>(initializer_list&lt;string&gt; il);</span><br><span class="line">	<span class="function"><span class="type">bool</span> <span class="title">empty</span><span class="params">()</span> <span class="type">const</span> </span>&#123; <span class="keyword">return</span> data-&gt;<span class="built_in">empty</span>(); &#125;</span><br><span class="line">	<span class="function">size_type <span class="title">size</span><span class="params">()</span> <span class="type">const</span> </span>&#123; <span class="keyword">return</span> data-&gt;<span class="built_in">size</span>(); &#125;</span><br><span class="line">	<span class="function"><span class="type">void</span> <span class="title">push_back</span><span class="params">(<span class="type">const</span> string &amp;s)</span> </span>&#123; data-&gt;<span class="built_in">push_back</span>(s); &#125;</span><br><span class="line">	<span class="function"><span class="type">void</span> <span class="title">pop_back</span><span class="params">()</span></span>;</span><br><span class="line">	<span class="function">string&amp; <span class="title">front</span><span class="params">()</span></span>;</span><br><span class="line">	<span class="function"><span class="type">const</span> string&amp; <span class="title">front</span><span class="params">()</span> <span class="type">const</span></span>;</span><br><span class="line">	<span class="function">string&amp; <span class="title">back</span><span class="params">()</span></span>;</span><br><span class="line">	<span class="function"><span class="type">const</span> string&amp; <span class="title">back</span><span class="params">()</span> <span class="type">const</span></span>;</span><br><span class="line">	<span class="function">StrBlobPtr <span class="title">begin</span><span class="params">()</span></span>;</span><br><span class="line">	<span class="function">StrBlobPtr <span class="title">end</span><span class="params">()</span></span>;</span><br><span class="line"><span class="keyword">private</span>:</span><br><span class="line">	shared_ptr&lt;vector&lt;string&gt;&gt; data;</span><br><span class="line">	<span class="function"><span class="type">void</span> <span class="title">check</span><span class="params">(size_type i, <span class="type">const</span> string &amp;msg)</span> <span class="type">const</span></span>;</span><br><span class="line">&#125;;</span><br><span class="line"> </span><br><span class="line"><span class="keyword">class</span> <span class="title class_">StrBlobPtr</span> </span><br><span class="line">&#123;</span><br><span class="line">	<span class="function"><span class="keyword">friend</span> <span class="type">bool</span> <span class="title">eq</span><span class="params">(<span class="type">const</span> StrBlobPtr &amp;lhs, <span class="type">const</span> StrBlobPtr &amp;rhs)</span></span>;</span><br><span class="line"><span class="keyword">public</span>:</span><br><span class="line">	<span class="built_in">StrBlobPtr</span>(): <span class="built_in">curr</span>(<span class="number">0</span>) &#123; &#125;</span><br><span class="line">	<span class="built_in">StrBlobPtr</span>(StrBlob &amp;a, <span class="type">size_t</span> sz = <span class="number">0</span>):</span><br><span class="line">		<span class="built_in">wptr</span>(a.data), <span class="built_in">curr</span>(sz) &#123; &#125;</span><br><span class="line">	<span class="function">string&amp; <span class="title">deref</span><span class="params">()</span> <span class="type">const</span></span>;</span><br><span class="line">	<span class="function">StrBlobPtr&amp; <span class="title">incr</span><span class="params">()</span></span>;</span><br><span class="line"><span class="keyword">private</span>:</span><br><span class="line">	shared_ptr&lt;vector&lt;string&gt;&gt; <span class="built_in">check</span>(<span class="type">size_t</span>, <span class="type">const</span> string&amp;) <span class="type">const</span>;</span><br><span class="line">	weak_ptr&lt;vector&lt;string&gt;&gt; wptr;</span><br><span class="line">	<span class="type">size_t</span> curr;</span><br><span class="line">&#125;;</span><br><span class="line"> </span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">StrBlob::check</span><span class="params">(size_type i, <span class="type">const</span> string &amp;msg)</span> <span class="type">const</span> </span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">if</span> (data-&gt;<span class="built_in">size</span>() &lt;= i)</span><br><span class="line">		<span class="keyword">throw</span> <span class="built_in">out_of_range</span>(msg);</span><br><span class="line">&#125;</span><br><span class="line"> </span><br><span class="line">StrBlob::<span class="built_in">StrBlob</span>(): <span class="built_in">data</span>(make_shared&lt;vector&lt;string&gt;&gt;()) &#123; &#125;</span><br><span class="line"> </span><br><span class="line">StrBlob::<span class="built_in">StrBlob</span>(initializer_list&lt;string&gt; il): <span class="built_in">data</span>(make_shared&lt;vector&lt;string&gt;&gt;(il)) &#123; &#125;</span><br><span class="line"> </span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">StrBlob::pop_back</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="built_in">check</span>(<span class="number">0</span>, <span class="string">&quot;pop back on empty StrBlob&quot;</span>);</span><br><span class="line">	data-&gt;<span class="built_in">pop_back</span>();</span><br><span class="line">&#125;</span><br><span class="line"> </span><br><span class="line"><span class="function">string &amp;<span class="title">StrBlob::front</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="built_in">check</span>(<span class="number">0</span>, <span class="string">&quot;front on empty StrBlob&quot;</span>);</span><br><span class="line">	<span class="keyword">return</span> data-&gt;<span class="built_in">front</span>();</span><br><span class="line">&#125;</span><br><span class="line"> </span><br><span class="line"><span class="function"><span class="type">const</span> string &amp;<span class="title">StrBlob::front</span><span class="params">()</span> <span class="type">const</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="built_in">check</span>(<span class="number">0</span>, <span class="string">&quot;front on empty StrBlob&quot;</span>);</span><br><span class="line">	<span class="keyword">return</span> data-&gt;<span class="built_in">front</span>();</span><br><span class="line">&#125;</span><br><span class="line"> </span><br><span class="line"><span class="function">string &amp;<span class="title">StrBlob::back</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="built_in">check</span>(<span class="number">0</span>, <span class="string">&quot;back on empty StrBlob&quot;</span>);</span><br><span class="line">	<span class="keyword">return</span> data-&gt;<span class="built_in">back</span>();</span><br><span class="line">&#125;</span><br><span class="line"> </span><br><span class="line"><span class="function"><span class="type">const</span> string &amp;<span class="title">StrBlob::back</span><span class="params">()</span> <span class="type">const</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="built_in">check</span>(<span class="number">0</span>, <span class="string">&quot;back on empty StrBlob&quot;</span>);</span><br><span class="line">	<span class="keyword">return</span> data-&gt;<span class="built_in">back</span>();</span><br><span class="line">&#125;</span><br><span class="line"> </span><br><span class="line"><span class="function">StrBlobPtr <span class="title">StrBlob::begin</span><span class="params">()</span> </span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">return</span> <span class="built_in">StrBlobPtr</span>(*<span class="keyword">this</span>); </span><br><span class="line">&#125;</span><br><span class="line"> </span><br><span class="line"><span class="function">StrBlobPtr <span class="title">StrBlob::end</span><span class="params">()</span> </span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">auto</span> ret = <span class="built_in">StrBlobPtr</span>(*<span class="keyword">this</span>, data-&gt;<span class="built_in">size</span>());</span><br><span class="line">	<span class="keyword">return</span> ret;</span><br><span class="line">&#125;</span><br><span class="line"> </span><br><span class="line">shared_ptr&lt;vector&lt;string&gt;&gt; StrBlobPtr::<span class="built_in">check</span>(<span class="type">size_t</span> i, <span class="type">const</span> string &amp;msg) <span class="type">const</span></span><br><span class="line">&#123;</span><br><span class="line">	<span class="keyword">auto</span> ret = wptr.<span class="built_in">lock</span>();</span><br><span class="line">	<span class="keyword">if</span> (!ret)</span><br><span class="line">		<span class="keyword">throw</span> <span class="built_in">runtime_error</span>(<span class="string">&quot;unbound StrBlobPtr&quot;</span>);</span><br><span class="line">	<span class="keyword">if</span> ( i &gt;= ret-&gt;<span class="built_in">size</span>() )</span><br><span class="line">		<span class="keyword">throw</span> <span class="built_in">out_of_range</span>(msg);</span><br><span class="line">	<span class="keyword">return</span> ret;</span><br><span class="line">&#125;</span><br><span class="line"> </span><br><span class="line"><span class="function">string &amp;<span class="title">StrBlobPtr::deref</span><span class="params">()</span> <span class="type">const</span> </span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">auto</span> p = <span class="built_in">check</span>(curr, <span class="string">&quot;dereference past end&quot;</span>);</span><br><span class="line">	<span class="keyword">return</span> (*p)[curr];</span><br><span class="line">&#125;</span><br><span class="line"> </span><br><span class="line"><span class="function">StrBlobPtr &amp;<span class="title">StrBlobPtr::incr</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="built_in">check</span>(curr, <span class="string">&quot;increment past end of StrBlobPtr&quot;</span>);</span><br><span class="line">	++curr;</span><br><span class="line">	<span class="keyword">return</span> *<span class="keyword">this</span>;</span><br><span class="line">&#125;</span><br><span class="line"> </span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="type">bool</span> <span class="title">eq</span><span class="params">(<span class="type">const</span> StrBlobPtr &amp;lhs, <span class="type">const</span> StrBlobPtr &amp;rhs)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	shared_ptr&lt;vector&lt;string&gt;&gt; l = lhs.wptr.<span class="built_in">lock</span>(), r = rhs.wptr.<span class="built_in">lock</span>();</span><br><span class="line">	</span><br><span class="line">	<span class="keyword">if</span> (l == r)</span><br><span class="line">		<span class="keyword">return</span> (!r || lhs.curr == rhs.curr);</span><br><span class="line">	<span class="keyword">else</span> </span><br><span class="line">		<span class="keyword">return</span> <span class="literal">false</span>;</span><br><span class="line">&#125;</span><br><span class="line"> </span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="type">bool</span> <span class="title">neq</span><span class="params">(<span class="type">const</span> StrBlobPtr &amp;lhs, <span class="type">const</span> StrBlobPtr &amp;rhs)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">return</span> !<span class="built_in">eq</span>(lhs, rhs);</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">class</span> <span class="title class_">TextQuery</span> </span><br><span class="line">&#123;</span><br><span class="line"><span class="keyword">public</span>:</span><br><span class="line">	<span class="keyword">using</span> line_no = StrBlob::size_type;</span><br><span class="line">	<span class="built_in">TextQuery</span>(ifstream&amp;);</span><br><span class="line">	<span class="function">QueryResult <span class="title">query</span><span class="params">(<span class="type">const</span> string&amp;)</span> <span class="type">const</span></span>;</span><br><span class="line"><span class="keyword">private</span>:</span><br><span class="line">	shared_ptr&lt;StrBlob&gt; file;</span><br><span class="line">	map&lt;string, shared_ptr&lt;set&lt;line_no&gt;&gt;&gt; wm;</span><br><span class="line">&#125;;</span><br><span class="line"> </span><br><span class="line">TextQuery::<span class="built_in">TextQuery</span>(ifstream &amp;infile): <span class="built_in">file</span>(<span class="built_in">make_shared</span>&lt;StrBlob&gt;())</span><br><span class="line">&#123;</span><br><span class="line">	string line;</span><br><span class="line">	string word;</span><br><span class="line">	line_no index = <span class="number">0</span>;</span><br><span class="line">	</span><br><span class="line">	<span class="keyword">while</span> (<span class="built_in">getline</span>(infile, line)) &#123;</span><br><span class="line">		file-&gt;<span class="built_in">push_back</span>(line);</span><br><span class="line">		++index;</span><br><span class="line">		<span class="function">istringstream <span class="title">strline</span><span class="params">(line)</span></span>;</span><br><span class="line">		<span class="keyword">while</span> (strline &gt;&gt; word) &#123;</span><br><span class="line">			<span class="comment">/* 消除词首和词尾的标点 */</span></span><br><span class="line">			<span class="keyword">if</span> (<span class="built_in">ispunct</span>(word[<span class="number">0</span>]))</span><br><span class="line">				word.<span class="built_in">erase</span>(<span class="number">0</span>, <span class="number">1</span>);</span><br><span class="line">			<span class="keyword">if</span> (<span class="built_in">ispunct</span>(word[word.<span class="built_in">size</span>()<span class="number">-1</span>]))</span><br><span class="line">				word.<span class="built_in">pop_back</span>();</span><br><span class="line">			<span class="keyword">if</span> (<span class="built_in">ispunct</span>(word[word.<span class="built_in">size</span>()<span class="number">-1</span>]))</span><br><span class="line">				word.<span class="built_in">pop_back</span>();</span><br><span class="line">			</span><br><span class="line">			<span class="keyword">if</span> (!wm[word])</span><br><span class="line">				wm[word] = make_shared&lt;set&lt;line_no&gt;&gt;();</span><br><span class="line">			wm[word]-&gt;<span class="built_in">insert</span>(index);</span><br><span class="line">		&#125;</span><br><span class="line">	&#125;</span><br><span class="line">&#125;</span><br><span class="line"> </span><br><span class="line"><span class="function">QueryResult <span class="title">TextQuery::query</span><span class="params">(<span class="type">const</span> string &amp;s)</span> <span class="type">const</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="type">static</span> shared_ptr&lt;set&lt;line_no&gt;&gt; <span class="built_in">nodata</span>(make_shared&lt;set&lt;line_no&gt;&gt;());</span><br><span class="line">	</span><br><span class="line">	<span class="keyword">auto</span> loc = wm.<span class="built_in">find</span>(s);</span><br><span class="line">	<span class="keyword">if</span> (loc == wm.<span class="built_in">end</span>())</span><br><span class="line">		<span class="keyword">return</span> <span class="built_in">QueryResult</span>(s, nodata, file);</span><br><span class="line">	<span class="keyword">else</span></span><br><span class="line">		<span class="keyword">return</span> <span class="built_in">QueryResult</span>(s, loc-&gt;second, file);</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="Ex12-33"><a href="#Ex12-33" class="headerlink" title="Ex12.33"></a>Ex12.33</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 添加如下成员函数</span></span><br><span class="line">set&lt;line_no&gt;::<span class="function">const_iterator <span class="title">begin</span><span class="params">()</span> <span class="type">const</span> </span>&#123; <span class="keyword">return</span> lines-&gt;<span class="built_in">begin</span>(); &#125;</span><br><span class="line">set&lt;line_no&gt;::<span class="function">const_iterator <span class="title">end</span><span class="params">()</span> <span class="type">const</span> </span>&#123; <span class="keyword">return</span> lines-&gt;<span class="built_in">end</span>(); &#125;</span><br><span class="line"><span class="function">shared_ptr&lt;StrBlob&gt; <span class="title">get_file</span><span class="params">()</span> </span>&#123; <span class="keyword">return</span> file; &#125;</span><br></pre></td></tr></table></figure>

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href="#Ex12-3"><span class="toc-number">3.</span> <span class="toc-text">Ex12.3</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-4"><span class="toc-number">4.</span> <span class="toc-text">Ex12.4</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-5"><span class="toc-number">5.</span> <span class="toc-text">Ex12.5</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-12-1-2"><span class="toc-number"></span> <span class="toc-text">Exercises Section 12.1.2</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-6"><span class="toc-number">1.</span> <span class="toc-text">Ex12.6</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-7"><span class="toc-number">2.</span> <span class="toc-text">Ex12.7</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-8"><span class="toc-number">3.</span> <span class="toc-text">Ex12.8</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-9"><span class="toc-number">4.</span> <span class="toc-text">Ex12.9</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-12-1-3"><span class="toc-number"></span> <span class="toc-text">Exercises Section 12.1.3</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-10"><span class="toc-number">1.</span> <span class="toc-text">Ex12.10</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-11"><span class="toc-number">2.</span> <span class="toc-text">Ex12.11</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-12"><span class="toc-number">3.</span> <span class="toc-text">Ex12.12</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-13"><span class="toc-number">4.</span> <span class="toc-text">Ex12.13</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-12-1-4"><span class="toc-number"></span> <span class="toc-text">Exercises Section 12.1.4</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-14"><span class="toc-number">1.</span> <span class="toc-text">Ex12.14</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-15"><span class="toc-number">2.</span> <span class="toc-text">Ex12.15</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-12-1-5"><span class="toc-number"></span> <span class="toc-text">Exercises Section 12.1.5</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-16"><span class="toc-number">1.</span> <span class="toc-text">Ex12.16</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-17"><span class="toc-number">2.</span> <span class="toc-text">Ex12.17</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-18"><span class="toc-number">3.</span> <span class="toc-text">Ex12.18</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-12-3-1"><span class="toc-number"></span> <span class="toc-text">Exercises Section 12.3.1</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-27-28"><span class="toc-number">1.</span> <span class="toc-text">Ex12.27 28</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-29"><span class="toc-number">2.</span> <span class="toc-text">Ex12.29</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-12-3-2"><span class="toc-number"></span> <span class="toc-text">Exercises Section 12.3.2</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-30"><span class="toc-number">1.</span> <span class="toc-text">Ex12.30</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-31"><span class="toc-number">2.</span> <span class="toc-text">Ex12.31</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-32"><span class="toc-number">3.</span> <span class="toc-text">Ex12.32</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex12-33"><span class="toc-number">4.</span> <span class="toc-text">Ex12.33</span></a></li></ol></div></div><div class="card-widget card-recent-post"><div class="item-headline"><i class="fas fa-history"></i><span>最新文章</span></div><div class="aside-list"><div class="aside-list-item no-cover"><div class="content"><a class="title" href="/blog/2022/05/17/%E3%80%8A%E7%AE%97%E6%B3%95%E8%AE%BE%E8%AE%A1%E6%89%8B%E5%86%8C%E3%80%8B%E9%9D%A2%E8%AF%95%E9%A2%98%EF%BC%9AChapter-1/" title="《算法设计手册》面试题：Chapter 1">《算法设计手册》面试题：Chapter 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